The present invention relates generally to method and apparatus for securing the tail of a convolutely wound web material, and, more particularly to a method and apparatus for securing the tail of wound webs of nonwoven materials that contain fibers bonded together by chemical, mechanical, heat, or solvent treatment material using ultrasonic means.
In the production of rolled web products for consumers, a rewinder or converter unwinds a large wound roll of web material, subjects the web material to desired conversions, such width slitting or perforations, and then rewinds the web into consumer sized, convolutedly wound rolls. The rewound rolls are typically removed from the rewinder and packaged using a separate machine and process. The rewound rolls have a tendency to unwind during this transition which complicates subsequent packaging operations. To prevent unintended unwinding of the rolls, it is common to secure the tail of the roll to the underlying layers of the web material.
As would be known to those of skill in the art, there are a number of well-known manners in which the tail, or end, of a convolutely wound web product may be secured or sealed to underlying layers in the roll. Common methods vary depending upon the web material and include gluing, moistening, mechanical deformation to join adjacent layers in the roll. In most commercially available embodiments, the tail securing method requires manipulation of the wound roll to apply the joining means sufficiently close to the tail to minimize the length of the unsecured end of the tail. Product packaging in which the product is accessed by unwinding the innermost layers first generally require only that the tail be secured to minimize problem potential during subsequent packaging operations, typically insertion of the roll into a container. Products that are externally unwound usually require a predetermined length of unsecured tail to provide a grasping point for the user to begin unwinding the roll.
Many products, including disposable wipes, are under increasing scrutiny regarding chemicals used in manufacture and production. Adhesives conventionally used to secure the tails in nonwoven polymer-based web that is typically used in disposable wipes are increasingly disfavored. Known ultrasonic welding methods are plagued by inconsistent performance and a tendency to bond numerous layers of the convoluted roll, leading to a high degree of waste as the packaged roll nears its end. It would be advantageous to provide a method and apparatus for securing the tail of a convolutely wound roll of nonwoven polymer-based web material using ultrasonic means which minimizes the layers of material secured in the bonding process while securing the tail sufficiently for subsequent packaging operations.